make regen-all now suggests running: make autoconf (GH-30893)

"make autoconf" also runs autoheader, whereas "autoconf" does not.

Author: vstinner

Makefile.pre.in

@@ -1185,7 +1185,7 @@ regen-all: regen-opcode regen-opcode-targets regen-typeslots \
 	regen-token regen-ast regen-keyword regen-frozen clinic \
 	regen-pegen-metaparser regen-pegen regen-test-frozenmain
 	@echo
-	@echo "Note: make regen-stdlib-module-names and autoconf should be run manually"
+	@echo "Note: make regen-stdlib-module-names and make autoconf should be run manually"
 
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 # Special rules for object files